The proposed work will be a continuation and an extension of the program sponsored by the USPHS during the last two years. Of prime interest will be the investigation of the effects of chronic elevation of the ratios of acetaldehyde to alcohol on mitochondrial respiration and on myocardial contractility. The study has been made possible because chronic elevations of this ratio can be accomplished by daily injections of pargyline. The second problem is a continuation and extension of the reversibility of damage to the biochemistry of subcellular elements produced by alcohol and/or acetaldehyde. Sobriety will commence at various intervals following prolonged administration of ethanol. Finally, since marked changes have been found in force-velocity relationship of glycerinated heart muscle fibers of dogs exposed to alcohol for several years, the activity of myosin ATPase in these heart muscles will be investigated.